thanks
i have a 28/12.50/15 et street .
my thoughts are to try the 4.88 gear and bring her out hard . my convertor is about 4500 but when cruising at 2700 rpm and whack the throttle it flashes to about 48/5000.
.
im not sure on the rule of thumb but i have a 12.5/8 inch long input turbo spline and i was told that that is a 1.82 first gear. the trans is a tci competition built by tci with manual forward pattern. i was told that a 12.5/8 long shaft ment it wasa 1.82.
a th350 has a 2.52 first gear i believe
th400 has a 2.42 .
thanks for the responses